Preventer Rigging -- Lessons from the Platino Disaster

[Pelagic]

Originally Posted by accomplice

They were in gale conditions, gusting to 48kt, with 2meter sea from the south and 3meter swell from the north. .

That was the info I was looking for as my phone bandwidth and size made it hard to read the report.

Were they in a race?

In those weather and sea conditions running with full main is high risk at best due to the chances of accidental gybe.

The bigger the boat the more suicidal it becomes as I have captained 65m sailing ships

Showing an appropriate foresail and a small patch of main sheeted in to slow down the roll would have kept the boat from being overpowered, which probably was the cause of the accidental gybe .

I agree with Dockhead, on the benefits of a split rig, but even then, I prefer to keep the booms midships and run with reduced foresail or loose footed stay sail to keep everyone safe.

[s/v Jedi]

Like so often, I disagree with much if not most in this thread. When something that is not worn out breaks, an engineering error was made, period. There is no “this is the best that can be done but it will fail if winds or waves are too high in which case we’re all doomed”

Then the recommendations to make it stronger: spectra lines, bigger pad eyes, bigger blocks... but there’s always gonna be a higher wave, a bigger gust. This is not how engineering works, you need to change the design to cope with overwhelming force. Overwhelming means it is too much for any strength rope, padeye etc.

The solution is to make a system that will give a little before forces approach the calculated breaking point. Not by letting go, not a weak link that self-sacrifices but by a controlled way to give a little until the force becomes controllable again (until shock has been contained and passed)

Aboard Jedi I simply did this by matching the holding force of a rope clutch with the rest of the preventer system. The padeyes, blocks and rope must all be stronger than the force at which the clutch starts slipping. This slipping absorbs the shock load and as soon as the forces reduce to below the clutch slipping load, the clutch is holding again and further trimming can be done.

Snap shackles should not be used. The boom must have a single braid Dyneema pendant on each side with eye splices at each end. One is cow-hitched to the boom and the other is hung over a cleat at the gooseneck end of the boom. The preventer line can be a simple polyester double braid but it needs to have an eye splice and then a simple soft shackle is used to connect to the pendant. If not for the clutch slipping first, the preventer line should be the weak point in the system.

[Don C L]

Important to remember they were in the process of furling the main and had it partly furled and they had not started furling the jib when the hydraulics were knocked out. Sounds like they really were disabled almost immediately.
I can imagine throwing a line OVER the boom and then lashing it down progressively tighter to slow the boom, but never to lasso the boom, that would be suicide.

[Montanan]

Originally Posted by a64pilot

I think this seems to offer the most logical dissertation yet, in particular a brake works by converting kinetic energy into heat, that energy has to go somewhere, so there may well be a point to where do to heating one just can’t be made to work that dumps the heat into the line.
However I’m sure one could be engineered so that what amounts to a disk brake and shoes would be where the energy was dumped into, so you put $250,000 into Engineering, development and manufacturing and couldn’t sell enough to break even.

With a proper boom brake activated there would be minimal kinetic energy to dissipate into the friction on the line and realize that the portion of the line that is subject to contact with the brake continues to shift as the boom SLOWLY moves athwartship, so the heat is not imposed only in one spot of the sturdy line. Think of slipping line around a chocker or a winch and letting friction occur on the line that is wrapped on the drum while you play out additional line on to the wrappage.

The kinetic energy of a non-rotating object is equal to 1/2 times the Mass times the square of the velocity of the mass, so if you keep the boom moving slowly the energy needed to be dissipated is comparatively modest.
Some boom brakes also have locks that one can be separately line activated from the cockpit with so as to inhibit further motion athwartship by the boom at whatever positioning of the boom relative to the centerline of the vessel you desire.

[Tillsbury]

What surprises me is that no-one has pointed out that the boat was designed and built with the traveller on the coach roof, presumably carefully engineered to take the loads. Some idiot decided to move the traveller from its out-of-the-way position to the worst possible place: between the cockpit and the helm. And on top of that, didn’t engineer it to take the loads.

When I sailed a 28 footer we had little option. The traveller ran by the companionway, and we got used to checking before sticking our necks out. You moved from cabin to cockpit at speed, after checking that you were not at risk of gybing. Even an arm outstretched to point at something from inside the cabin could have been taken off by the main sheet coming across. One advantage of a larger boat is that you can remove this danger area.

On the other hand, it did instil in me an ability to feel a gybe coming way before it happened, so perhaps that’s why I rarely have trouble nowadays.

Spending the money to move the traveller and create the possibility of this disaster happening is something I will never understand.

[El Pinguino]

Originally Posted by Tillsbury

What surprises me is that no-one has pointed out that the boat was designed and built with the traveller on the coach roof, presumably carefully engineered to take the loads. Some idiot decided to move the traveller from its out-of-the-way position to the worst possible place: between the cockpit and the helm. And on top of that, didn’t engineer it to take the loads.

When I sailed a 28 footer we had little option. The traveller ran by the companionway, and we got used to checking before sticking our necks out. You moved from cabin to cockpit at speed, after checking that you were not at risk of gybing. Even an arm outstretched to point at something from inside the cabin could have been taken off by the main sheet coming across. One advantage of a larger boat is that you can remove this danger area.

On the other hand, it did instil in me an ability to feel a gybe coming way before it happened, so perhaps that’s why I rarely have trouble nowadays.

Spending the money to move the traveller and create the possibility of this disaster happening is something I will never understand.

That and much more was all discussed here ....... http://www.cruisersforum.com/forums/...ng-167804.html

Wasn't on the coachroof... was on an arch just frd of the helm ..same position as later but on arch not deck... there is a photo in the report of her arriving in Gulf Harbour with the arch.

The issue with no one near the helm at the time of the incident was due to that dodgy set up with the wheel right aft on what was essentially a centre cockpit boat. Not the only boat built with that bollocky arrangement... I think it was so that the helmsman could be down the back doing the full 'look at me, look at me' thing while the admiring ladies could be sitting in the shade under the dodger drinking drinks with little umbrellas in them.

[Tillsbury]

Sorry yes, an arch not the coach roof. Same deal, though, you could walk to the helm without going anywhere near the danger area.

A lot of larger yachts have helms way back and cockpit area forward that is purely for sitting around in, not sailing the boat. Most of those, though, have an aft companionway giving direct access from below to the helm position. That would have helped no end on Platino, even after removing the arch.

[Tetepare]

Originally Posted by Kenomac

Bad things can happen even when you do everything correctly. Our preventer on our 53 broke three weeks ago even though it was rigged the correct way... from the end of the boom, the preventer run all the way forward to the bow cleat. All it took was a 15 knot wind from dead astern, then punching in a goto heading on the chartplotter. The boat suddenly and without warning turned itself 60 degrees to starboard due to an auto pilot compass malfunction, then before I could get behind the helm and hit standby... snap! The preventer broke.

Fortunately, nothing else broke, nobody was hurt and only a forward stanchion was slightly bent. But stuff happens, and that’s one great feature of a center cockpit boat... it places you in a very safe location when things do go wrong. The entire gybe occured in less than maybe 5-10 seconds.

That’s why I am concerned when people tell dreamers to go ahead and sail the world on their first boat, a 40’foot plus.

Most people can handle one thing going wrong. The experienced can handle two. Experts three.

The problem with sailboats is that when one crisis hits it causes two more. Without the ability to prioritize, new sailors can be in a very dangerous place.

[CassidyNZ]

Originally Posted by s/v Jedi

The solution is to make a system that will give a little before forces approach the calculated breaking point. Not by letting go, not a weak link that self-sacrifices but by a controlled way to give a little until the force becomes controllable again (until shock has been contained and passed)

In my opinion the solution lies in sailing the vessel in a way that prevents a crash gybe. Yes, an unpredictable sea complicates things - all the more reason to bring the wind more on the beam. Sailing downwind in the 160’s to 180’s in 45kn with any amount of main up in an unpredictable rolly sea is seriously unwise.

What hasn’t been mentioned here (is in the report) and probably a more important lesson than how to rig a preventer, is that all of the people on Platino were very experienced ocean voyagers and from what I got out of the report, each member believed that all the others knew what they were doing. No discussion, no plan for MOB, no safety briefing, no plan in fact for anything going feral. That is the single most important issue in my view, why things went so badly wrong.

For the record, we were 100nm from Platino on the same night in the same weather. I had two crew, both seasick, both scared, both “had enough”, I turned and sailed home. Yes my boat is smaller but everything on my boat is specced for the size of the boat in the same way the gear on Platino was. The difference in outcomes was that I made better choices. And those that think I’m being big-headed, we survived with no breakages in a smaller boat. My crew were frightened but they made it home. Say no more.

Oh, and I wonder about the discussion surrounding the “scary” 2 to 3 metre seas. Huh?!? Three metre seas on an ocean crossing to or from NZ are almost routine as are multiple wave trains. It rarely gets less than 2m.

For those that haven’t read the full report, if you are a voyager it’s essential reading, there are lots of learnings there.

[Cpt Pat]

May I ask a stupid question? Why use a preventer at all instead of using a boom brake, like a Dutchman brake? Then, if the main does get taken aback (back winded), the boom can swing slowly across with the energy absorbed by the brake. I realize the problem the preventer is expected to prevent is the boom slamming alee when the main is taken aback; but rapidly slewing the stern against the rudder by the boom held in place and the boat being put way over on its lee side by the main seems nearly as bad. And then, there's the prospect of a bent boom when it is held in place without relief, along with the deadly catastrophic problem described here.

Is this a case of: "we've always done it this way" justification? Is there yet another asinine racing rule prohibiting a boom brake?

[RaymondR]

Originally Posted by Pelagic

That was the info I was looking for as my phone bandwidth and size made it hard to read the report.

Were they in a race?

In those weather and sea conditions running with full main is high risk at best due to the chances of accidental gybe.

The bigger the boat the more suicidal it becomes as I have captained 65m sailing ships

Showing an appropriate foresail and a small patch of main sheeted in to slow down the roll would have kept the boat from being overpowered, which probably was the cause of the accidental gybe .

I agree with Dockhead, on the benefits of a split rig, but even then, I prefer to keep the booms midships and run with reduced foresail or loose footed stay sail to keep everyone safe.

We can argue about the detail until the cows come home but the proximal cause of the incident was that the boat was not being sailed conservatively enough for the prevailing conditions.

Since I gained the status of senior citizen even in light conditions where I sail the boat downwind wing and wing with main and genoa I jibe the boat by furling the genoa and doing a 270. Call me a silly old bastard if you like but I cannot stand the banging and crashing of the classic chinese jibe anymore.

[Suijin]

Originally Posted by Tetepare

That’s why I am concerned when people tell dreamers to go ahead and sail the world on their first boat, a 40’foot plus.

Most people can handle one thing going wrong. The experienced can handle two. Experts three.

The problem with sailboats is that when one crisis hits it causes two more. Without the ability to prioritize, new sailors can be in a very dangerous place.

And I'm this case they had one mortally injured crew member on the boat and another knocked off the boat. The very definition of "fog of war" when it comes to the how long it takes to assess what's happened and make sound, well considered decisions regarding how to deal with the circumstances.

If it were me, I assume my first I instinct would be to focus my attention on those two crew members and assess what could be done to increase their odds of survival. The crippled boom would recede in Importance in my mind as I grappled with options in an obviously difficult and confusing situation, even if hindsight revealed getting control of it as central to everyone's collective best chances

[Cpt Pat]

Originally Posted by RaymondR

We can argue about the detail until the cows come home but the proximal cause of the incident was that the boat was not being sailed conservatively enough for the prevailing conditions.

Since I gained the status of senior citizen even in light conditions where I sail the boat downwind wing and wing with main and genoa I jibe the boat by furling the genoa and doing a 270. Call me a silly old bastard if you like but I cannot stand the banging and crashing of the classic chinese jibe anymore.

Silly old bastard: no. Prudent experienced seaman: yes.

[JPA Cate]

With our double preventers continually rigged, we never have crash gybes. We ease the main across under control of the preventer, and then tighten it on the new gybe. That is one of the best things about them, and why Jim first started using them when singlehand racing in the ocean on a 30 footer. [Yes, we did have a broken boom, once, but a whole lot easier to deal with its 17 ft, that what Platino had., and a broken boom is sort of ho hum, compared to one instant death, and one by drowning. They couldn't even keep an eye on the one who got washed overboard, because they were trying to stay alive, themselves. What a terrible event to have on your conscience.]

NZ Cassidy did good with his crew, brought them safely back, showed due care for their safety and the preparation of his boat, and the reminder that sea conditions were normal for the time of year and area. He did not have the disadvantage of Platino's arch traveler, and consequent out of control boom. To me, its size and weight, plus the sheer trauma of the event: one second everything's okay, next one, two dead men--your voyage friends, and a seriously injured boat with a killer boom! Exhilarating sail to disaster in the blink of an eye, and a lot of noise! So yes, matching the gear to the loads is really important. We know big race boats have massy gear and are able to gybe around marks, etc., without killing people. Jedi's right about that, it wasn't done right, and what suffering resulted.... No wonder they decided to just let it go after the rig came down and all efforts had failed. All would have been suffering emotionally.

Ann

[Tillsbury]

Platino didn’t have an arch traveller. That’s the point.